Discipline of Physiotherapy, School of Health Sciences, The University of Newcastle, Callaghan, NSW 2308 Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141 The Australian Lung Foundation, Lutwyche, QLD, 4030 School of Physiotherapy, Faculty of Health Sciences, Australian Catholic University, North Sydney, NSW, 2060 BakerIDI, Alice Springs, Northern Territory, Australia School of Medicine and Dentistry, James Cook University, Cairns, Queensland.